JPlag is a system that finds similarities among multiple sets of source code files. This way it can detect software plagiarism and collusion in software development.

collusion-detection, java, plagiarism-check, plagiarism-detection, plagiarism-prevention, software-plagiarism, source-code-analysis


Download and Run JPlag

Download a released version - all releases ar single-JAR releases.

Type java -jar jplag-yourVersion.jar in a console to see the command line options.


Assume that we want to check students' solutions that are written in Java 1.7.

Each student solution is in its own directory, say student1, student2, and so on. All solutions are in a common directory, say exercise1.

To run JPlag, simply type java -jar jplag-yourVersion.jar -l java17 -r /tmp/jplag_results_exerise1/ -s /path/to/exercise1

  • -l java17 tells JPlag to use the frontend for Java 1.7
  • -s tells JPlag to reccurse into subdirectories; as we assume Java projects, we'll very likely encounter subdirectories such as student1/src/
  • -r /tmp/jplag_results_exercise1 tells JPlag to store the results in the directory /tmp/jplag_results_exercise1

Building JPlag

To build and run a local installation of JPlag, you can use the pom.xml in this directory (aggregator). It builds JPlag and the available frontends.

To generate single modules run mvn clean generate-sources package in the base directory; if you want a single file then run mvn clean generate-sources assembly:assembly inside the jplag directory. You will find the JARs in the respective target directories. If you build a single JAR, it will be generated in jplag/target.

Web Service

Installing, running and maintaining a local web service is not recommended as the web service uses outdated libraries and (really) needs polishing.

If you want to do it anyway: atujplag is the client, webservice is the - yepp - web service.

Improving JPlag

We're happy to incorporate all improvements to JPlag into this code base. Feel free to fork the project and send pull requests.

Adding new languages

Adding a new language frontend is quite simple. Have a look at one of the jplag.frontend projects. All you need is a parser for the language (e.g., for ANTLR or for JavaCC) and a few lines of code that sends the tokens (that are generated by the parser) to JPlag.